package
{
    import flash.geom.*;
    import flash.display.*;
    import flash.geom.Vector3D;

    public class Nadir extends Sprite
    {
        public function Nadir()
        {
            var lineDrawing:MovieClip = new MovieClip();
            this.addChild(lineDrawing);

            var lineA:Vector3D = new Vector3D(0, 0, 0);
            var lineB:Vector3D = new Vector3D(stage.stageWidth, stage.stageHeight, 0);
            var point:Vector3D = new Vector3D(400, 120, 0);
            var v:Vector3D = getNadir(lineA, lineB, point);

            lineDrawing.graphics.lineStyle(1);
            lineDrawing.graphics.moveTo(lineA.x, lineA.y);
            lineDrawing.graphics.lineTo(lineB.x, lineB.y);
            lineDrawing.graphics.moveTo(point.x, point.y);
            lineDrawing.graphics.lineTo(v.x, v.y);

        }
        public function getNadir(lineA:Vector3D, lineB:Vector3D, point:Vector3D):Vector3D
        {
            var d, ca, sa, mx:Number;
            var result:Vector3D = new Vector3D(0, 0, 0);

            var v:Vector3D = new Vector3D(lineB.x, lineB.y, lineB.z);
            v = v.subtract(lineA);
            d = v.length;
            ca = v.x / d;
            sa = v.y / d;

            mx = (-lineA.x + point.x) * ca + (-lineA.y + point.y) * sa;

            result.x = lineA.x + mx * ca;
            result.y = lineA.y + mx * sa;

            return result;
        }
    }
}